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Battery cable question

Discussion in 'The Hokey Ass Message Board' started by bob8823, Nov 27, 2013.

  1. bob8823
    Joined: Apr 16, 2011
    Posts: 39

    bob8823
    Member

    I'm building a C cab and due to space restrictions, I have to mount the battery towards the back. Will #2 AWG cable be what I would need to use for a 10' run. Thanks.
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 48,314

    squirrel
    Member

    You could probably get away with it with a smaller engine that cranks easily. If you give us a bit more info, like how long the cables will be (both positive and negative), as well as the engine type and modifications to it, maybe we could guess better
     
  3. 68vette
    Joined: Jul 28, 2009
    Posts: 306

    68vette

    In my 51 shoebox with a 305, I put the battery in the trunk, ran ONE welding cable( auto shops call it that) up the the starter, the ground cable of course, was very short as it just attached to the frame under the battery area..
     
  4. Shaun1162
    Joined: Feb 22, 2010
    Posts: 833

    Shaun1162
    Member

    I would personally not use #2 gauge wire- It might cover you, but the bigger the gauge the better.

    I recall seeing a guy that made his battery cables for a car out of old jumper cables (If I recall they were #2 gauge)... It was a pretty long run, and suffice to say the cable didn't last long trying to crank the 327.

    I'd do with 1/0 or 2/0 (when you ask for it, say 1 ought or 2 ought). My '33 stock car was pretty tricky to find a spot for a battery, and I ended up using an Odyssey PC680. I'd say there's at least 10 feet of cable, and I ran it with 1/0. I have no trouble spinning over the starter in my 283.
     

  5. 1971BB427
    Joined: Mar 6, 2010
    Posts: 6,681

    1971BB427
    Member
    from Oregon

    It really depends on what type of cable you run. Not all cable is rated the same ampacity, and the finer the strands, the more ampacity it holds. A #2 is rated 100 amps in it's lowest rating, but in fine strand machine tool, or welding cable the ampacity is double at 200 amps.
    I'd go with #2 if you buy the welding cable, or machine tool cable, but not the coarse strand cable.
     
  6. upspirate
    Joined: Apr 15, 2012
    Posts: 2,273

    upspirate
    Member

    I used welding cable on my 36 p/u with battery under the bed.
    Positive length to the starter, and a short negative to the frame near the battery.

    Don't forget a ground cable to a CLEAN (no paint) point on the block (I used a trans to engine bolt) from the frame up front,and a ground cable to the body if steel,or a ground buss bar if glass body
     
  7. keyster
    Joined: Dec 27, 2011
    Posts: 26

    keyster
    Member

    The local battery shop recommended 2/0.
    Partially because of the small price difference between 1 and 2/0.

    DC doesn't travel very well and needs large conductors and good mechanical connections.

    I used 1/0 on my remote battery, but I haven't fired the engine yet.......

    K
     
  8. raidmagic
    Joined: Dec 10, 2007
    Posts: 1,438

    raidmagic
    Member

    HA that's funny I read your post then thought Hey my dad is building a C cab and he is in Brandon too.....Hi dad!
     
  9. 68vette
    Joined: Jul 28, 2009
    Posts: 306

    68vette

    I ran my 51 ford for 8 years without one problem.....it was on the the second battery after the 5th year...the car always started like the battery was right beside the starter....when I build one, I usually drive it trouble free for years and years....
     

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  10. drptop70ss
    Joined: May 31, 2010
    Posts: 1,172

    drptop70ss
    Member
    from NY

    I used #2 copper for the trunk mounted battery in the 37 Buick, left over from a 100 amp subpanel installation in my shop. Works great, spins the engine over easily at all temps. BIggest issue IMO is to have a good ground. I run the hot line from the battery to the starter, ground from the block to the frame up front and a ground from the frame to the battery in the back. Frame is also grounded to the body but with a smaller factory style ground strap, everything else is #2 stranded copper.
     
  11. bob8823
    Joined: Apr 16, 2011
    Posts: 39

    bob8823
    Member

    I'll try to answer everyone's questions here. Positive cable will be ten feet long. Negatives will only be a foot or so, just to ground to the frame and to ground the motor also. Motor is a stock 283, no mods. Also, no ac, will only have radio, lights, starter draw, gauges and fuel pump. Starter will be the heaviest draw.

    The cable I was looking at was #2 AWG welding cable type k. I also looked at the 1/0 and the 2/0 but couldn't find out the difference between them and the #2 AWG. I believe the AWG is a little smaller but don't know how much. Anyone know what the size difference is??

    Appreciate the help.

    Bob

    ps, Hi Steve.
     
  12. :rolleyes:How about some pics of that C-cab:D
     
  13. Size difference? 2/0 will about twice the size of #2, 1/0 roughly midway between.

    The starter draw is the draw you need to worry about. There's a number of factors to consider; will your motor start easily and quickly? With a small motor like a 283 (I assume a mild motor; no high-compression here) a #2 will probably be adequate. But with a larger motor, low battery, extended starting time, or worn starter the draw could be more than the #2 can handle. Small wire with high amp motor loads heats up; as it heats, it's ability to deliver voltage degrades rather quickly, causing the motor amps to climb yet more, causing more heat, so forth and so on...

    The 2/0 will handle just about anything you throw at it, the #2 may not be able....
     
  14. PushnFords
    Joined: Dec 2, 2011
    Posts: 52

    PushnFords
    Member

    Around me it is hard to find 1/0. For batteries located in the engine compartment I usually use #2 welding cable. If it is a long run then I switch to 2/0 welding cable. The welding cable is a lot more flexible so it is easier to route. If you are worried about size due to space considerations you could find the draw for your starting circuit and do the math...there are online calculators I've seen. I have 25' of 2/0 welding cable in the shop I bought off eBay for a fraction of what Napa/Carquest wanted that I'm using on a tractor. The OD including insulation is right around .060"
     
  15. That should be .6"....
     
  16. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,406

    Flat Ernie
    Tech Editor

    Any decent welding shop can get quality welding cables in any gauge. I made some using 2/0 that would start a semi. For long runs (anything over about six feet, IMO), they are the only thing I'd consider.
     
  17. squirrel
    Joined: Sep 23, 2004
    Posts: 48,314

    squirrel
    Member

    My wife has an off-topic little car that has a factory trunk mounted battery...and the cables look like #6 gauge wire. Stock, from the factory. And it starts every time.

    If you can afford 2/0 wire, go for it. If not, you might be able to get away with less.
     
  18. bob8823
    Joined: Apr 16, 2011
    Posts: 39

    bob8823
    Member

    Guess I'll be going with the 2/0 welding cable, thanks for all the help. Here's a pic. Couldn't figure out how to upload more than one.
     

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  19. bob8823
    Joined: Apr 16, 2011
    Posts: 39

    bob8823
    Member

    Got it, the second pic was too big, kept getting rejected.
     

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  20. LongT
    Joined: May 11, 2005
    Posts: 957

    LongT
    Member

    On my T-bucket I used 1/0 welding cable. 6 years and no problems. I saw somewhere to not use welding cable forget why but it worked for me.

    Bill
     
  21. woodiewagon46
    Joined: Mar 14, 2013
    Posts: 1,821

    woodiewagon46
    Member
    from New York

    I would go with 1/0 welding cable, there is a huge difference between #2 and 1/0 cable. You won't regret it. You can get any size cable and cable ends from McMaster-Carr.
     
  22. 1971BB427
    Joined: Mar 6, 2010
    Posts: 6,681

    1971BB427
    Member
    from Oregon

    Sorry, but this is just wrong info. Circular mils of #2, vs. 1/0 and 2/0 are not double and halfway between.
    #2 has a diameter of 258 mil
    #1/0 diameter is 325 mil
    #2/0 diameter is 365 mil

    So as you can see 1/0 is about 20% larger than #2 and 2/0 is about 10% larger than 1/0, and about 35% larger than #2.
     
  23. I was only giving very approximate sizes; the CM numbers are only for the wire, when you add the insulation to them that changes the overall size. And the larger sizes generally get somewhat thicker insulation.
     
  24. squirrel
    Joined: Sep 23, 2004
    Posts: 48,314

    squirrel
    Member

    ...and current carrying ability is proportional to cross section area, which is proportional to diameter squared.

    (sorry for the engineering words)
     
  25. 1971BB427
    Joined: Mar 6, 2010
    Posts: 6,681

    1971BB427
    Member
    from Oregon

    Current carrying capacity is directly related to circular mils, but also to density. A solid wire carries the most ampacity, but is a poor choice for automotive or vibration. A 12-16 strand conductor is nowhere near the current capacity of a 100 strand in the same size.
    Insulation also affects current rating, as it relates to temperatures, but although insulation does increase in thickness with size, there's very little difference in insulation between the three sizes referred to. What will really affect insulation thickness is temperature rating of the insulation.
    Lots of other things effect current carrying capability, or rating, but not relative to automotive uses really.
     
  26. trollst
    Joined: Jan 27, 2012
    Posts: 1,999

    trollst
    ALLIANCE MEMBER

    The only thing I'd add is run the negative all the way to a bell housing bolt.
     
  27. As long as the two ends are attached to clean, continuous metal you usually won't need the ground cable ran along with the positive. You do want to use a big enough ground strap from the engine to whatever you bonded the negative to in the back (frame or body), then a smaller one if needed for any other bonding.

    I scrapped out a '86 Jag XJS recently, and a few things I salvaged was the battery cables (factory trunk-mounted battery) and a couple of bulkhead fittings. The fittings are pretty cool, bolt them through a hole in the firewall and they're insulated from ground, and the best part is there's a #10 threaded stud inside the car for power pick-up. The 'main' cable attaches to this, then you use a short jumper to the starter. The cables are about 2/0, and while finer strand than building wire, not as fine as welding cable. but nice cable nonetheless; sealed at both ends, with battery terminals on one end.
     
  28. 1971BB427
    Joined: Mar 6, 2010
    Posts: 6,681

    1971BB427
    Member
    from Oregon

    Yep, I run one good cable to the frame in back, and one from frame to block in front. Good bare connection at both ends and never a problem. same setup on my car for three years now, and never failed to crank right up.
     
  29. inline 292
    Joined: Aug 25, 2006
    Posts: 296

    inline 292
    Member

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